Check Engine Light is On

I'd suspect the thermostat is stuck open and needs to be replaced. On a modern vehicle the engine needs to reach normal operating temperature, usually 195°F, within a certain amount of time from a cold start up. The time limit is usually 10 minutes. If that doesn't happen the check engine light will come on and a trouble code will be stored in the computer. With the temperature gauge reading low I'm suspecting that's what it is. Visit your local auto parts store and have them scan the computer for trouble codes to confirm this. Most stores will do it for free! Hope that helps! Jim